1. Field of the Invention
This invention relates generally to camera lenses, and more particularly, to a novel mounting ring and lens accessory construction for positioning and locking lens accessories at the front of the lens.
2. Description of the Prior Art
It often is desirable in the use of the conventional camera lenses to attach one or more accessory discs at the front of the lens to achieve special photographic effects. For example, selected accessory aperture discs may be positioned at the front of the lens to reduce the amount of light which reaches the film in bright light conditions and to give a sharper image and increase the depth of field. Also, in order to compensate for bright light conditions and when using relatively fast films, it may be desirable to use a selected filter disc positioned at the front of the lens. On occasion, it may even be desirable to use both an aperture disc and a filter disc concurrently mounted on the lens to achieve a desired effect.
Varying photographic conditions and films dictate which selected one or more of any of a wide variety of aperture, filter or other special effect discs should be used by mounting the same to the front of the camera lens. Therefore, it is necessary that such discs be removably mountable in a quick and convenient manner to permit the user to change accessory with a minimum of effort. It also is necessary that the accessory, once mounted, be firmly and securely positioned on the lens so as not to be unintentionally dislodged.
Various camera lens accessory mounting devices of the type with which the present invention is concerned are known in the art. For example, the following patents disclose attaching means for camera lens accessories and for mounting photo vignetting devices to camera lenses:
______________________________________ U.S. Pat. Nos. 3,122,077 3,940,775 3,527,151 4,013,347 3,761,162 4,107,716 3,774,992 4,124,859 3,879,741 4,126,878 3,885,242 4,213,686 French Patent 1,185,926 ______________________________________
The attaching members disclosed in said patents are of relatively complex and special construction which are cumbersome for the user to handle. The present invention provides an accessory mounting member which is of relatively uncomplicated construction and yet achieves the desired advantages of permitting quick and convenient mounting and de-mounting of lens accessories to the front end of the lens which are securely positioned thereon when so mounted.